The pimary purpose of this project is to compare zinc absorption and excretion in pregnant and nonpregnant women. Three dietary sources of zinc will be fed to the women while they are confined to the metabolic unit. One diet is an egg-white-based liquid diet adequate in all nutrients and containing 20 mg zinc from zinc sulfate. The other 2 diets are blenderized diets of natural foods. Both diets contain about 16 mg zinc, but 70% of the zinc in one diet comes from animal sources and 70% in the other diet is from plant source. Preliminary results from the metabolic studies show that zinc utilization is altered greatly by the state of pregnancy. Total serum zinc decreases about 25% and is prmarily due to the fall in serum albumin and consequently albumin-bound zinc. In comparison to nonpregnant women, pregnant women retain about 1.0 mg zinc daily. Since the urinary excretion of zinc was actually greater in the pregnant than the nonpregnant women, zinc retention in pregnancy seems to be accomplished by eitheer an increase in zinc absorption or a decrease in intestinal zinc excretion. Further studies on zinc absorption are underway. Because zinc utilization is altered by pregnancy, it is evident that standards for normal serum and urinary zinc concentrations have to be developed for pregnant women. After completing measurements of serum, urinary, hair and salivary zinc levels of pregnant women fed the recommended intake, we plan to develop sandards which will then be used to evaluate the zinc status of free living pregnant women.